A Low-Carbohydrate Diet Improves Glucose Metabolism in Lean Insulinopenic Akita Mice Along With Sodium-Glucose Cotransporter 2 Inhibitor.

Objective: A low-carbohydrate diet (LC) can be beneficial to obese subjects with type2 diabetes mellitus (T2DM). Sodium-glucose cotransporter 2 inhibitor (SGLT2i) presents prompt glucose-lowering effects in subjects with T2DM. We investigated how LC and SGLT2i could similarly or differently influence on the metabolic changes, including glucose, lipid, and ketone metabolism in lean insulinopenic Akita mice. We also examined the impacts of the combination. Methods: Male Akita mice were fed ad libitum normal-carbohydrate diet (NC) as a control or low-carbohydrate diet (LC) as an intervention for 8 weeks with or without SGLT2i treatment. Body weight and casual bold glucose levels were monitored during the study, in addition to measuring TG, NEFA, and ketone levels. We quantified gene expressions involved in gluconeogenesis, lipid metabolism and ketogenesis in the liver and the kidney. We also investigated the immunostaining analysis of pancreatic islets to assess the effect of islet protection. Results: Both LC and SGLT2i treatment reduced chronic hyperglycemia. Moreover, the combination therapy additionally ameliorated glycemic levels and preserved the islet morphology in part. LC but not SGLT2i increased body weight accompanied by epididymal fat accumulation. In contrast, SGLT2i, not LC potentiated four-fold ketone production with higher ketogenic gene expression, in comparison with the non-treated Akita mice. Besides, the combination did not enhance further ketone production compared to the SGLT2i alone. Conclusions: Our results indicated that both LC and SGLT2i reduced chronic hyperglycemia, and the combination presented synergistic favorable effects concomitantly with amelioration of islet morphology, while the combination did not enhance further ketosis in Akita mice.

Apolipoprotein E genetic polymorphism influence the susceptibility to nephropathy in type 2 diabetes patients.

BACKGROUND: An association between Apolipoprotein E (Apo E) alleles and genotypes and diabetic nephropathy (DN) was suggested, but with inconsistent results. We tested the relationship between serum lipids, Apo E alleles and genotypes with type 2 diabetes (T2DM), and DN pathogenesis. METHODS: Study subjects comprised 1389 normoglycemic controls, and 1422 T2DM patients, of whom 825 were normoalbuminuric (DWN), and 597 presented with nephropathy (DN). RESULTS: Significantly lower Apo ε2, and higher Apo ε4 allele frequencies was seen among T2DM patients than controls. Significantly higher frequency of ε3/ε4, and lower frequencies of ε3/ε3, ε2/ε3, and ε4/ε4 carriers was seen among T2DM cases. Apo ε2-carrying individuals were more frequently found in controls than in patients, while significantly higher frequency of ε4-carrying genotypes was seen in T2DM cases. Significantly higher ε2, and lower ε3 allele frequencies were noted for DN group compared to DWN group. Significantly higher frequency of ε2-containing ε2/ε3 and ε2/ε4, and lower frequencies of ε3/ε3 carriers was seen among DN cases. Apo ε3/ε3 was associated with higher total cholesterol, LDL-cholesterol, and triglyceride levels in DN patients, and significantly higher triglyceride levels were seen in ε2/ε3-carrying DN patients. Logistic regression analysis confirmed the association of Apo ε3-containing ε3/ε3, ε2/ε3, and ε3/ε4, and Apo ε2-containing ε2/ε4 with DN, after controlling for key covariates. CONCLUSION: The results of this case-control study provide evidence that the ε2 and ε3 alleles of APOE modify lipid profile, and constitute independent risk factors of DN in type 2 diabetes. The molecular mechanisms underlying this risk is discussed.

Pancreatic glucose-dependent insulinotropic polypeptide (GIP) (1-30) expression is upregulated in diabetes and PEGylated GIP(1-30) can suppress the progression of low-dose-STZ-induced hyperglycaemia in mice.

AIMS/HYPOTHESIS: Glucose-dependent insulinotropic polypeptide (GIP) is a peptide hormone released from gut K cells. While the predominant form is GIP(1-42), a shorter form, GIP(1-30), is produced by pancreatic alpha cells and promotes insulin secretion in a paracrine manner. Here, we elucidated whether GIP(1-30) expression is modulated in mouse models of diabetes. We then investigated whether PEGylated GIP(1-30) can improve islet function and morphology as well as suppress the progression to hyperglycaemia in mice treated with low-dose streptozotocin (LD-STZ). METHODS: We examined pancreatic GIP immunoreactivity in rodent diabetic models. We synthesised [D-Ala(2)]GIP(1-30) and modified the C-terminus with polyethylene glycol (PEG) to produce a dipeptidyl peptidase-4 (DPP-4)-resistant long-acting GIP analogue, [D-Ala(2)]GIP(1-30)-PEG. We performed i.p.GTT and immunohistochemical analysis in non-diabetic and LD-STZ diabetic mice, with or without administration of [D-Ala(2)]GIP(1-30)-PEG. RESULTS: Pancreatic GIP expression was concomitantly enhanced with alpha cell expansion in rodent models of diabetes. Treatment with DPP-4 inhibitor decreased both the GIP- and glucagon-positive areas and preserved the insulin-positive area in LD-STZ diabetic mice. Body weight was not affected by [D-Ala(2)]GIP(1-30)-PEG in LD-STZ or non-diabetic mice. Treatment with GIP significantly ameliorated chronic hyperglycaemia and improved glucose excursions in LD-STZ mice. Treatment with GIP also reduced alpha cell expansion in the islets and suppressed plasma glucagon levels compared with non-treated LD-STZ mice. Additionally, [D-Ala(2)]GIP(1-30)-PEG preserved beta cell area via inhibition of apoptosis in LD-STZ mice. CONCLUSIONS/INTERPRETATION: Our data suggest that GIP(1-30) expression is upregulated in diabetes, and PEGylated GIP(1-30) can suppress the progression to STZ-induced hyperglycaemia by inhibiting beta cell apoptosis and alpha cell expansion.